Portable crane



R. CRAIG.

PORTABLE CRANE.

APPLICATION FILED FEB. a, 1 919.

Patented June 7, 1921.

2 SHEETS-SHEET I- R. CFH-QEGD PORTABLE QRANE.

APPLICATION FILED FEB-8,1919.

Patehted June 7, 1921..

2 SHEETS-SHEET 2- ROBERT CRAIG, OF BERKELEY, CALIFORNIA.

PORTABLE GRAN E.

Specification of Letters Patent.

Patented June "2, 1921.

Application filed. February 8, 1919. Serial No. 275,906.

To all whom it may 'a'oncem:

Be it known that I, ROBERT CRAIG, a citizen of the United States, residing at Berkeley, in the county of Alameda and State of California, have invented a new and useful Portable Crane, of which the following is a specification.

My invention relates to a certain well known form of portable crane which is used principally in machine shops, garages and. automobile repair shops, being mounted on wheels so that it can be readily transported from place to place.

The object of my invention is to provide such a crane in which standard structural steel forms or rods are used as tension members and in which cast iron parts are used in compression, this combination producing a very strong construction at a low cost.

A further object of the invention is to provide a portable crane which will be comparatively light in weight and which will have a very long over hang.

A still further and important object of the invention is to provide a crane which is so constructed that'certain of the structural steel members will deflect noticeably long before any of the parts approach their breaking stresses, thus providing a crane having some elasticity so that the danger of total failure under load is very remote.

Other objects and advantages will be evident hereinafter.

Referring to the drawings, which are for I illustrative purposes only,

Figure l is a side elevation of one form of my invention.

Fig. 2 is a section. on a plane represented by theline 2-2 of Fig. 1.

Fig. 3 is an end elevation.

Fig. 4 is a side elevation on an enlarged scale showing the ratchet and pawl mechamsm.

Fig. 5 is a section through the locking screw on the front wheel.

Fi 6 is an elevation on an enlarged scale illOWlIlg the method of securing the crank In the form of my invention illustrated in these figures, two structural base members 11 are provided, these members being preferably of I beam form as shown. cured by means of bolts 12 to the rear end of each of these members are rear axle castings 13 which carry rearaxles 14 on each of which one of'two rear wheels 15 is free to revolve. Secured between themembers 11, intermediate of the ends thereof, is a table casting 20 which is provided with a I ing about the pivot pin 31 and supporting Q the front casting 30 is a caster 32 which carries a front axle 33 on which a front wheel 34 is free to turn. A handle 35 is plvoted on a pin 36 carried in the caster 32, the handle being provided with a cross bar 37. The handle 35 is used to drag the crane about from place to place on the wheels 15 and 34 and is also used to turn-the front wheel 15 into any desired position, the caster 32 turning about the pivot pin 31.

Secured about the mast 22 is a boom casting 40, this casting ,being held in place against any up or down movement on the mast 22 partly by means of a bolt 41 and partly by two truss rods 42 which are secured at the bottom in the table 20 by means of nuts 43 and which are secured at the top by means of nuts 44 in an open slot in a cap 45 which is seated on the top of the mast 22. A projection 46 forming a part of the casting 40 extends outwardly at right angles to the mast 22, being forked to receive the truss rods 42 which are bent as shown, the mast 22, the projection 46 and casting 61 which carries a pin 62 on which a rear sheave 63 turns. The casting 61 is prevented from turning on the boom 60 by means of a set screw 64. The casting 61 is slotted to receive the rear end of two tension rods 65, the other ends of which are seated in open slots in the side of the cap 45. The cap 45 is prevented from turning by means of a set screw 66. A front sheave pin 71 is secured in the cap 45 and 'a front sheave turns freely thereon. chain or cable 72 provided with a hook 73 asses over the rear sheave 63 and the front s eave 70, passing downwardly therefrom to a long' drum 80, this drum being turned down to form journals at either end whlch turn freely in bearings 81 secured to the angle 'iron members 50.

The drum 80 is provided with a s ur gear 82, the chain or cable 70 being fastened to this gear at or near the hub thereof. The gear 82 meshes with a carried on a pinion shaft 84 WlllCh turns in bearings 85 carried on the members 50.

A crank hub 86 is secured to the extreme end of the shaft 84 outside one of the bearings 85. The hub 86 has an opening formed therein in which a crank bar 87 is free to slide radially, this crank bar being locked in any position by a set screw 871. A crank handle 88 is secured to the end of the bar 87.

Located on the shaft 84 between the bearings 85 is a ratchet wheel 89 which is en ;with the wheel 34 the crane may be hauled about from place toplace by means of the handle 35, the front wheel being turned in any direction by that handle. The crane may be backed up' to the work wherever it may be, the wheels 15 passing at each side of the work if it is resting on the floor or passing under the work if it is raised from the floor as is the case where parts are to be removed from an automobile or where the load is to be lifted from a lathe or planer bed or the. like. The hook 73 is hooked to the load to be lifted and the drum 80 is-rotated by means 'ofthe handle 7 88, the pinion 83 and the gear 82 and their associated parts. Theload can be heldat any point by dr0pping the pawl 90 into engagement with the ratchet'wheel 89.

fter the load is raised and su ported by the crane it can be transported from place to place by pulling the handle 35. If it is desired to hold the load at any point the 'crane can be locked by a suitable manipulation of the star-wheel 92. The bar 87 can be moved along a radius through the hub 86 and locked in any place therein by means of the set screw 871 so that the eifective radius of the handle. 88 b can bei'v'a'ried to suit the work to be lifted. Ifflije'load. is small the handle 88 is set in .cl'oseto the axis of the shaft 84 and relatively rapid lifting can be accomplished.

inion 83 the handle 88.

the load and crane by noted that the handle 88 does not pass into the space ahead of the mast 22 except when the handle 88 is considerably extended. It is'thus possible to run the mast 22 close up against the bed of a lathe or up against the radiator of an automobile and yet have considerable room in which to manipulate bending or otherwise distorting under a load before actually breaking. The crane is so proportioned that the cast iron members whichare wholly in compression have an excess of strength so that the tension 7 and fiexion members will deflect before an actual breakage takes place in the compression members. As a result of this form of construction the crane will bend before breaking thus giving warning of an overload. This is very important as it is often necessary for men to work under the suspended load on the crane, and these men are liable to becaught by the load if anything gives way suddenly.

It should also be noted that the mast 22 and the boom 60 are seated in sockets at either end and that they are forced into these sockets by the load so that it is not necessary to provide any particular fastening to hold them in place, the set screws which press against the 'mast 22 and boom 60 being provided merely to-prevent rotation of the various parts.

What I claim is 1. In a portable crane, a base; a three wheel support therefor; a mast socketed to said base intermediate said points of support of said wheels on said base; casting secured to said mast intermediate of the ends thereof; an oblique brace connecting said boom casting. to the forward end of said base; a strut integral with and projecting from said boom casting in the direction of the forward end of said truck; a truss rod secured at either end to said mast and passing over the outer end of said strut; a boom having itsforward end secured in said boom casting; and a tension rod secured a boom' at one end to the upper. end of said mast and at the other end to the end of said 2. In a" portable crane, a base; a three .wheel support therefor; a mast socketed to aesome casting secured to said mast intermediate of the ends thereof; an oblique brace connecting said boom casting to the forward end of said base; a winch carried on said brace; a strut integral with and projecting from said boom casting in the direction of the forward end of said truck; a truss rod secured at either end .to said mast and passing over the outer end of said strut; a boom having its forward end secured in said boom casting; and a, tension rod secured. at one end to the up er end of said mast and at the other end to t e end of said boom.

3. In a portable crane, a base; a three wheel support therefor; a mast socketed to said base intermediate said points of support of said wheels on said base; a boom casting secured to said mast intermediate of the ends thereof; an oblique tension brace connecting said boom casting to the forward end of said base; a strut integral with and projecting from said boom casting in the direction of the forward end of'said. truck; a truss rod secured at either end to said mast and passing over the outer end of said strut; a-boom having its forward end secured in said boom castin and a tension rod secured at one endto t e upper end of saidmast and. at the other end to the end of said boom.

4. In a portable crane, a base; a three wheel support therefor; a mast soeketed to said base intermediate said points of support of said wheels on said base; a boom ing over the outer end of said strut; a boom I having its forward end secured in said boom casting; and a tension rod secured at one end, to the upper end of said mast and at the other end to the end of said boom.

In testimon whereof, I have hereunto set my hand at os Angeles, California, this 31st day of'Januar'y, 1919.

ROBERT C i 

